GB989144A - Polyether polyols and polyurethane foams derived therefrom - Google Patents

Abstract

The invention comprises polyoxypropylene anhydrohexitols of hydroxyl number 350-750 containing no more than 10 mol. per cent polyoxypropylene glycol. The compounds may be prepared by reacting propylene oxide with an anhydrohexitol at 90-150 DEG C. in the absence of water and in the presence of a basic catalyst. Sufficient propylene oxide may be added to form chains 2-10 units long on some or all of the hydroxyl groups. Anhydrohexitols specified are 1,4-, 1,5-, 2,6-, and 3,5- anhydrosorbitol and anhydromannitol and 1,4: 3,6-dianhydrosorbitol or mixtures thereof. They may be obtained by reducing the corresponding hexose. 0.01-0.5 molecules of catalyst may be used per hydroxy group. Catalysts specified are the hydroxides, methoxides and ethoxides of sodium and potassium and the alkali metal alcoholates of the anhydrohexitols. The reaction may be carried out under a nitrogen atmosphere and at elevated pressure. A solvent may be employed, e.g. dimethyl formamide, dimethyl sulphoxide, a hydrocarbon, ether or heterocyclic base. A basic solvent may also function as a catalyst. In examples (3-6) the product is purified by dilution with water and passage down a cation-exchange resin column.ALSO:A polyurethane foam may be produced by adding a polyisocyanate and a blowing agent to a polyol of OH number 350-750 prepared by interacting an anhydro-hexitol and propylene oxide at 90-150 DEG C., in the presence of a basic catalyst and in the absence of water. Anhydrohexitols specified are 1,4-, 1,5-, 2,5- and 3,6- anhydrosorbitol, 1,4-, 1,5-, 2,6- and 3,6- anhydromannitol, 1,4,3,6 - di - anhydrosorbitol and dianyhydromannitol. Mixtures of isomers may be used. Catalysts specified are the hydroxides, methoxides and ethoxides of sodium and potassium and the alkali metal alcoholates of the anhydrohexitols. 0.01-0.5 equivalents may be used per equivalent of hydroxyl group. The propylene oxide addition reaction may be carried out at atmospheric or an elevated pressure of an inert gas, e.g. N2 and a solvent may optionally be used. Solvents specified are: n-hexane, ligroin, benzene, xylene, dioxane, diethylene glycol, diethyl ether, dimethyl formamide, dimethyl sulphoxide, N - acylmorpholines, N - methylpyrrolidone, N - ethyl - pyrrolidone, pyridine, picoline and tri-n-butylamine. The addition product may have 2-10 oxypropylene units per molecule and may contain up to 10% of polyoxypropylene glycol in admixture. In polyurethane production the polyols of the invention may be mixed with other polyols, e.g. linear polyethers, polyesters, aromatic polyethers, and sorbitol centred polyethers. Isocyanates specified are: ethylene diisocyanate, ethylidene diisocyanate, propylene-1,2 - diisocyanate, butylene - 1,2 - diisocyanate, hexylene - 1,6 - diisocyanate, cyclohexylene - 1, 2 - diisocyanate, m - phenylene diisocyanate, tolylene - 2,4 - diisocyanate, tolylene - 2,6 - diisocyanate, 3,31 - dimethyldiphenyl - 4, 41 - diisocyanate, 3,31 - dichlorodiphenyl - 4, 41 - diisocyanate, triphenylmethane - 4, 41,411 - triisocyanate, naphthalene-1, 4-diisocyanate reaction products of these with: hexane-1,2,6-triol, 1,1,1-trimethylolpropane, glycerol, propylene glycol, dipropylene glycol, tripropylene glycol, or mono-, di- or tri-ethylene glycol. Blowing agents specified are H2O, CCl2, F2, CCl3F and azo compounds The reaction may be a continuous process, a one-shot process or a prepolymer two-stage reaction. Other additives may be catalysts, e.g. N-methyl morpholine, triethylamine, N,N, N1, N1-tetra(2-hydroxypropyl) ethylene diamine, dibutyltin dilaurate, dibutyltin di(2-ethylhexoate), stannous octoate and stannous 2-ethylhexoate, foam stabilizers, e.g. polydimethylsiloxane, alkylsilane-polyoxyalkylene block copolymers, sorbitan monostearate and glycerol monooleate, pigments, fillers, e.g. glass fibre, nylon fibre, wool, polyvinyl chloride, mica, silica gel, alumina gel, asbestos and zinc oxide, antioxidants and stabilizers. The products may be rigid and of uniform cell size.